1. Technical Field
The present disclosure relates to a display device and an electronic apparatus that can detect an external proximity object, specifically, a display device with a touch detection function and an electronic apparatus that can detect the external proximity object based on a change in capacitance.
2. Description of the Related Art
In recent years, a touch detection device that can detect an external proximity object, what is called a touch panel, has been attracting attention. The touch panel is used for a display device with a touch detection function in a manner mounted on or integrated with a display device such as a liquid crystal display device. In the display device with a touch detection function, various button images and the like are displayed on the display device, so that information can be input using the touch panel instead of a typical mechanical button. The display device with a touch detection function having such a touch panel does not require an input device such as a keyboard, a mouse, and a keypad. Accordingly, use of the display device with a touch detection function tends to expand in portable information devices such as cellular telephones as well as computers.
Examples of type of the touch detection include, but are not limited to, an optical type, a resistance type, a capacitive type, and the like. A capacitive touch detection device is used for portable devices and the like, has a relatively simple structure, and can achieve low power consumption. For example, Japanese Patent Application Laid-open Publication No. 2011-138154 describes a touch panel in which a transparent electrode pattern is made invisible. Japanese Patent Application Laid-open Publication No. 2007-264393 describes a technique to suppress, in a liquid crystal display device including a light-transmissive light condensing sheet, a light and shade pattern (moire) caused by interference between a prism arrangement pitch of the light condensing sheet and a pixel pitch of a liquid crystal display panel.
In the display device with a touch detection function, a pixel of the display panel overlaps with a touch detection electrode. In the touch detection electrode, translucent conductive oxide such as indium tin oxide (ITO) is used as material of the transparent electrode. Although the touch detection electrode is transparent, it has a certain refractive index. Accordingly, in the display device with a touch detection function, a slit (hole pattern) is provided in the transparent electrode pattern of the touch detection electrode so that the touch detection electrode is made invisible with human's eyes.
By arranging a pattern of a dummy electrode having the same light shielding property as that of the touch detection electrode between patterns of the touch detection electrode, it is also possible to reduce possibility that the pattern of the touch detection electrode is visually recognized. The pattern of the dummy electrode not contributing to touch detection should be finely divided by slits so as to make capacity difference with respect to the touch detection electrode.
There may be a difference between a wavelength of light that passes through the transparent electrode pattern of the dummy electrode from the pixel of the display panel and reaches a person, and a wavelength of light that passes through the slit (hole pattern) from the pixel of the display panel and reaches the person. The difference in the wavelengths of light emerges as a change from color that should be originally displayed, and a fringe (color moire) of a color shift pattern (hereinafter, referred to as a moire fringe) may be visually recognized depending on a viewing angle at which the person views the display panel.
For the foregoing reasons, there is a need for a display device with a touch detection function and an electronic apparatus that can prevent the moire fringe of the display panel caused by the dummy electrode from being visually recognized.